One of the major unresolved questions in biology is the mechanism by which such organic nutrients as sugars are transferred through cellular membranes. The mechanism of sugar absorption in the intestine is localized within the brush border region of the intestinal epithelial cell. Our study is directed towards the identification of the molecules in the membrane, involved in the interaction with sugar during absorption. The brush border is available in isolated form and can be subfractionated into distinct and morphologically identifiable components. Such isolation allows the use of the recently developed photo affinity labeling technique for the identification of the receptor molecules involved in the transport process. A derivative of glucose possessing a photo reactive group would be prepared. This compound should still possess the necessary specificity for the active transport process and would be preferentially bound by the transporting site. Upon photo activation a reactive carbene or nitrene would be generated forming a covalent linquage with the protein. A radioactively labeled compound could be prepared for identification of the molecule. Eventually an unlabeled molecule could be isolated providing us with the means to learn about the nature of its operation, and an understanding of the molecular nature of sugar transport in the intestine. This approach could be extended towards the understanding of transport of nonionic organic nutrients in mammalian cells in general.